/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/SubRegionRemesher.h
It is initialized from a set of Triangles and the initial ROI boundary is inferred from those triangles.
class FRestrictedSubRegionRemesher : public [UE::Geometry::FSubRegionRemesher](API\Plugins\DynamicMesh\FSubRegionRemesher)